In the evening cravings for sweets rise

Molecular clocks in the brain's reward center control our appetite for sweet foods.

Who does not know that: After a sumptuous dinner in the restaurant, the waiter walks past the table and suggests a look at the dessert menu. Although you are already full, the perspective of a delicious dessert makes you sin again. A high reward value of food makes us regularly take in more calories than our body really needs. One differentiates here between homeostatic (= due to the pure energy requirement) and hedonic (= "lust"-driven) appetite. The latter seems particularly pronounced in the hours before bedtime.

Using mouse experiments, Lübeck researchers led by Christiane Koch, Kimberly Begemann and Henrik Oster from the Institute of Neurobiology at the CBBM were able to show that these two different types of appetite each have their own daily rhythm, which in turn is controlled by distinct molecular circadian clocks in the hypothalamus (homeostasis) and in the so-called limbic system (hedonics). An important messenger for hedonic rhythms is dopamine. It makes the animals more susceptible to snacks such as chocolate during the early resting phase, and makes them literally overeat. When the researchers manipulated the clock function in the dopamine cells, this effect did no longer occur and the animals become "chocolate-resistant".

"Comparable studies in humans have not yet been completed, but the results point in the same direction. For the first time, our data show a mechanism by which homeostatic and hedonic appetite rhythms can be regulated separately in terms of time and space," say Prof. Oster and Prof. Schmid from the Institute of Endocrinology and Diabetes, the heads of the study.

The project was financially supported by the German Research Foundation within the Collaborative Research Center 134 "Mechanisms of Appetite Regulation" and the Volkswagen Foundation. Colleagues from the Max Planck Institute for Metabolism Research in Cologne were also involved.

Publication: Circadian regulation of hedonic appetite in mice by clocks in dopaminergic neurons of the VTA. Koch CE, Begemann K, Kiehn JT, Griewahn L, Mauer J, M E Hess, Moser A, Schmid SM, Brüning JC, Oster H. Nat Commun. 2020 Jun 17; 11 (1): 3071. doi: 10.1038 / s41467-020-16882-6.

Contact: Prof. Dr. Henrik Oster / henrik.oster(at)uni-luebeck.dewww.neurobio.uni-luebeck.de/